DOMRectReadOnly：x 属性
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since 2020年1月.
备注： 此特性在 Web Worker 中可用。
DOMRectReadOnly 接口的只读属性 x 表示 DOMRect 原点的 x 坐标。